There are various interfaces that are common across a number of SWANS layers
and tie the system together. The most important interface of this kind is Message. It represents a packet transfered along the network stack and it
must be timeless (or immutable). Components at various layers define their own
message structures. Many of these instances recursively store messages within
their payload, thus forming a message chain that encodes the hierachical
header structure of the message. Other common elements include a node, node
location, protocol number mapper and miscellaneous utilities.